Total income - personal, family, combined parental, extended family, and household 2013 Census (information about this variable and its quality)

##Related variables

• Grouped total personal income
• Grouped total household income
• Grouped total family income
• Grouped total extended family income
• Grouped combined parental income for couples with child(ren)

These variables are for output on small geographic areas (ie meshblocks, area units, or user-defined combinations of these) or population groups. The categories of these variables are more aggregated than other income variables.

##Where the data comes from

Question 31 on the individual form.

Data from the individual form is used to derive the following variables:

• Combined parental income for couples with child(ren)
• Total extended family income
• Total family income
• Total household income.

How these income variables are derived

The definitions of 'Family' and 'Extended family' are restricted to people living in the same household. Therefore, although financial interdependence can exist across households, the family income and extended family income data relates to people living in the same household.

As total personal income is collected in income ranges (eg $25,001–$30,000), and not as an actual dollar income (eg $29,500), in order for total family income to be calculated, a representative income is determined for each total personal income range. Household surveys have been used to calculate these representative incomes. Total family income is derived by adding together the median total personal incomes of each member of the family nucleus who is aged 15 years and over. As a result of this calculation, a family income category is assigned to the family.

Household income is calculated in a similar way to family income, except that all people in the household who are aged 15 years and over are included in the calculation.

Extended family income is calculated in a similar way to family income, except that all people in the extended family who are aged 15 years and over are included in the calculation.

Refer to the section 'Further information about this data' below for details about the collection and output of these income variables.

##How this data is classified

Total personal income

11 Loss

12 Zero income

13 $1-$5,000

14 $5,001-$10,000

15 $10,001-$15,000

16 $15,001-$20,000

17 $20,001-$25,000

18 $25,001-$30,000

19 $30,001-$35,000

20 $35,001-$40,000

21 $40,001-$50,000

22 $50,001-$60,000

23 $60,001-$70,000

24 $70,001-$100,000

25 $100,001-$150,000

26 $150,001 or more

99 Not stated

The same classification is used for the other income variables.

Note that two new bands were added in the 2013 Census. The category $50,001-$70,000 was split into two income brackets: $50,001-$60,000 and $60,001-$70,000. A new income band was added above ‘$100,001 or ‘more’, which resulted in the inclusion of following new categories: $100,001-$150,000 and $150,001 or more.

For further information about this classification, refer to the:

• 2013 Census data dictionary
• Statistical standard for income bands.

For background information on classifications and standards, refer to the Classifications and related statistical standards page.

##Subject population

Total personal income

The subject population is census usually resident population count aged 15 years and over.

Total family income

The subject population is families in private occupied dwellings.

Combined parental income for couples with child(ren)

The subject population is couples with children in private occupied dwellings.

Total extended family income

The subject population is extended families in private occupied dwellings.

Total household income

The subject population is households in private occupied dwellings.

The subject population is the people, families, households, or dwellings to whom the variable applies.

##Non-response and data that could not be classified

Non-response

The non-response rate is the percentage of the subject population that was coded to ‘Not stated’. 'Non-response' is when an individual gives no response at all to a census question that was relevant to them.

If personal income information is missing for an individual 15 years and over in a household, family, or family nucleus then the family/extended family/household income is allocated to not-stated unless the combined incomes fall in the highest income bracket of $150,001 or more. This situation results in higher non-response rates for total income for families and households. Larger and more complex households are most likely to have missing income information. As a result, non-response for total extended family income is much higher, at over a quarter of such households.

For individual substitute records, the missing income information is coded to ‘Not stated’. Family, parental income for couples with child(ren), extended family, and household incomes are derived variables.

Non-response rates for 2013:

• Total personal income: 9.7 percent, of which 4.9 were substitute records
• Total family income: 11.2 percent
• Combined parental income for couples with child(ren): 8.6 percent
• Total extended family income: 27.0 percent
• Total household income: 15.0 percent.

Non-response rates for 2006:

• Total personal income: 10.2 percent, of which 3.4 were substitute records
• Total family income: 13.9 percent
• Combined parental income for couples with child(ren): 11.3 percent
• Total extended family income: 31.0 percent
• Total household income: 16.2 percent.

Non-response rates for 2001:

• Total personal income: 11.1 percent, of which 2.4 were substitute records
• Total family income: 16.1 percent
• Combined parental income for couples with child(ren): 13.8 percent
• Total household income: 18.5 percent
• Total extended family income: 35.5 percent.

Refer to the section 'Further information about this data' below for details about the collection and output of these income variables.

For more information on non-response and substitutes records, refer to the 2013 Census data user guide.

##How this data is used

Data from this variable is used:

• to formulate social and economic policy and monitoring programmes
• by the Ministry of Education in determining decile rankings for schools receiving government funding
• in developing the New Zealand Deprivation Index
• for research and planning by central and local government agencies.

##Data quality processes

All census data was checked thoroughly during processing and evaluation, to ensure that it met quality standards and is suitable for use. These quality checks included extensive edits. All data must meet minimum quality standards to make it suitable for use.

Quality level

A quality level is assigned to all census variables: foremost, defining, or supplementary.

These variables are defining variables. Defining variables cover key subject populations that are important for policy development, evaluation, or monitoring. These variables are given second priority in terms of quality, time, and resources across all phases of a census.

Mode of collection impacts – online form compared with paper form

The online forms had built-in editing functionality that directed respondents to the appropriate questions and ensured that their responses were valid. As a result of this, data from online forms may be of higher overall quality than data from paper forms. The significance of this will depend on the particular type of analysis being done. There will always be a mode effect but this cannot be measured. Statistics NZ design and test to minimise the effects of mode for all questions.

There were differences between how the forms were completed online and on paper for this variable:

• On the online form, only people who gave a New Zealand address in question 5 and were 15 years of age or older were able to respond to the total income question. When forms were completed on paper it was possible for overseas visitors and those respondents under 15 years of age to respond to this question.
• The online form allowed only one response to be selected for the income question. If a further response was selected, the response given previously disappeared. Multiple responses to this question were possible when forms were completed on paper.

##Quality assessment of data and data quality issues for this variable

Overall quality assessment

Moderate: fit for use–- with some data quality issues to be aware of. 2013 Census variable quality rating scale gives more detail.

Issues to note

• Non-response rates for 2013:

  • Total personal income: 9.7 percent, of which 4.9 were substitute records

  • Total family income: 11.2 percent

  • Combined parental income for couples with child(ren): 8.6 percent

  • Total extended family income: 27.0 percent

  • Total household income: 15.0 percent.

  • Because of high non-response rates, total household income and total extended family income are considered: Poor: fit for use – but use with caution due to some significant data quality issues.

  • Caution should be used when interpreting income data, because of the relatively high percentage in the ‘Not stated’ category.

  • Since family, household, and extended family income are derived from combining total personal income data for all adult members of a family, extended family or household, any missing personal income information affects response rates for total family, extended family, and household income. The total personal income of an absentee cannot be included in the calculation of these variables. Where there was one or more absentee aged 15 years or over, the income for the family, extended family, or household was set to 'Not stated' unless the accumulated income was already $150,001 or more. Likewise, if someone had not stated their income, the income for the family, extended family, or household was set to ‘Not stated’ unless the $150,001 or more threshold had already been reached. This has affected the quality of these variables and care should be taken when using them. The effect becomes more marked as the number of people in the family, extended family, or household increases.

  • High non-response rates can lead to bias in the data. This bias affects the aggregates and the distribution with the proportion of people in low-income bands being under-counted. The bias will mean that the data is not fit for use for certain purposes. Distributional statistics like averages and medians will be biased by the undercount of people in the low-income bands, while disparities at regional or ethnic group level may be understated for the regions and ethnic groups with high non-response rates. Population-based funding models that use income as a variable, and small area regional analysis for territorial local authorities and others, will also be affected by the bias.

For more information on non-response and substitute records, refer to the 2013 Census data user guide.

##Comparing this data with previous census data

This data is highly comparable with the 2006 Census data. Changes in the data over this time period can generally be interpreted as real changes. There may be a small component of change over time that is due to minor changes in the collection, definition, or classification of the data.

The changes for 2013 included splitting the $50,001–$70,000 band (to $50,001–$60,000 and $60,001–$70,000) and adding a band above $100,001 ($150,001+).

This data is broadly comparable with the 2001 Census data. Changes in the data over this time period may be partly due to changes in the collection, definition, or classification of the data rather than to real change.

The changes for 2013 included splitting of the $50,001–$70,000 band (to $50,001–$60,000 and $60,001–$70,000) and adding a band above $100,001 ($150,001+).

The changes for 2006 included splitting of the $30,001–$40,000 income band into two: $30,001–$35,000, $35,001–$40,000.

The 2006 and 2013 questionnaires had a note directing people to the help notes to help them determine their income. This note was not present in 2001.

There has been an improvement in non-response rates in 2013 because people who selected 'No source of income' but did not answer the total income question have been allocated to zero income. This edit was not carried out in previous years.

For time series data on this variable, users will need to aggregate bands or request customised data tables.

##Comparing this data with data from other sources

Census is the only information source that provides comprehensive information for small areas and small populations. However alternative sources of information about this subject are available:

• New Zealand General Social Survey (NZGSS)
• Household Economic Survey (HES)
• New Zealand Income Survey (NZIS)
• Linked Employer-Employee Database (LEED)
• Quarterly Employment Survey (QES)
• The user guide for wage and income measures

Data from these alternative sources may show differences from census data for several reasons. These could be due to differences in scope, coverage, non-response rates, data being collected at different periods of time, alternative sources being sample surveys and as such subject to sampling errors, or differences in question wordings and method of delivery (self-administered versus interviewer-administered). Data users are advised to familiarise themselves with the strengths and limitations of individual data sources before comparing with census data.

##Further information about this data

All percentages in census publications have been calculated using 'Total stated' as the denominator.

When using this data, be aware of the following:

• In order to add different income bands together, each band needs to be allocated a representative value. As census does not provide any details about the distribution of incomes within the bands, representative values are calculated for each income band using data from a survey which collects more detailed income data than census. In 2006, these were calculated from Survey of Family, Income, and Employment (SoFIE) data and for 2013 will be calculated from Household Economic Survey (HES) data. The representative value for each band is the median value (half are above and half below) for those in that band in the more detailed survey. The representative value may not always be the mid-point of the band because the distribution within a band isn't even across that band.
• The representative values for all those who are present in the household on census night and who stated their income are added together. If there are no people absent and everyone in the household answered the income question, then the correct band is allocated. For example, if the sum of the representative values for the household is $73,532 then the total household income band allocated is $70,001 to $100,000.
• If the amount summed is less than the top band ($100,001 or more in 2006 and $150,001 or more in 2013), and some people were either absent or did not state their income, then the household income is set to ‘Not stated’. However, if the sum of the representative values is in the maximum band, then the household is designated in the top income band for household income, even if some people are absent or did not respond.
• Where medians are provided, these should be used with caution so as not to give an impression of being a precise figure – which they are not. Medians are calculated for those that stated an income. Statistics NZ only outputs median incomes to the nearest $100.
• The time reference periods are different for income variables and for other variables that may be cross-tabulated with income variables. For example, 'Work and labour force status' relates to the week prior to census day, while sources of personal income relates to the previous 12 months ending on census day, and 'Total income' relates to the 12 months ending on 31 March 2013. It cannot therefore be assumed that someone employed in the previous week has been employed all year and received only wage and salary income

Caution is advised when analysing income data by ethnic group because of the high non-response rate of certain ethnic groups and changes to the ethnicity classification. The non-response rate was highest for Pacific peoples and lowest for European. Non-response rates for 2006 and 2013 were as follows:

Contact our Information Centre for further information about using this variable.